Technical Field
The present disclosure relates to ultrasonic probes and to methods of controlling ultrasonic probes.
Description of the Related Art
As is known, ultrasonic probes find widespread use in various sectors, amongst which also that of imaging diagnostics, where they are used in ultrasonographic scanners or ultrasonic tomography scanners.
An ultrasonic probe, for example, but not exclusively, for ultrasonography or ultrasonic tomography in general comprises an array of transducers housed in a package together with respective excitation and read circuits, which are governed by a control unit.
The transducers are configured to convert pressure waves into electrical signals and vice versa and may, for example, be piezoelectric transducers or else membrane capacitive transducers.
The excitation and read circuits are alternately connected to the transducers for generating ultrasound pulse trains (for example, at a frequency comprised between 2 MHz and 20 MHz) during a transmitting step and receiving return echoes, caused by variations of acoustic impedance in the medium in which the pulses are transmitted, during a receiving step.
Switching between the transmitting configuration and the receiving configuration is controlled both because the read circuits, at low voltage, have to be continuously protected from the high voltages (even higher than 100 V) used by transmission circuits and because disturbance may occur and reception of the return echoes may be jeopardized. Switching should further be fast, also to enable sonographic investigation in the near field, e.g., in the more superficial portion of the tissue or other body being examined. The return echoes, in fact, may not be correctly received if the read circuits and the transducers are not stably biased.
The problems linked to switching between the transmitting configuration and the receiving configuration are particularly felt for arrays in which each transducer has a single respective terminal accessible individually, whereas a further terminal is in common with corresponding terminals of the other transducers. On the other hand, both for reasons of costs of production of the transducers and on account of their smaller overall dimensions, probes of this type are better suited to integration and are normally preferred to probes in which the transducers have both of the terminals accessible individually.